He's a cold-blooded mass-murdering clown

And now fans have been given insight into just how Heath Ledger became immersed into the dark world of the Joker.

While his official cause of death was an accidental overdose many have always believed the Australian actor struggled after he created his Batman villain.

It’s been five years since his tragic death, but Heath Ledger’s performance as the Joker in “The Dark Knight” remains one of Hollywood’s most memorable, chilling villains ever to hit the big screen. Ledger prepared for the role by “reading all the comic books I could that were relevant to the script and then just closing my eyes and meditating on it,” he told Empire in 2007. “I sat around in a hotel room in London for about a month, locked myself away, formed a little diary and experimented with voices — it was important to try to find a somewhat iconic voice and laugh. I ended up landing more in the realm of a psychopath — someone with very little to no conscience towards his acts. He’s just an absolute sociopath, a cold-blooded, mass-murdering clown, and Chris has given me free rein. Which is fun, because there are no real boundaries to what The Joker would say or do. Nothing intimidates him, and everything is a big joke”

Video footage of that diary has emerged, thanks to Reddit, from a German documentary show called “Too Young To Die.” The show interviewed the actor’s father, Kim Ledger, on an episode about the late star, who shared the diary.

The diary provides a disturbing glimpse into the psyche of the Joker, holding clippings from Batman comics, pictures from Stanley Kubrick’s “A Clockwork Orange,” playing cards, pictures of clowns and more. The video, in French, has been translated to English via YouTube:

This is the Joker’s diary. In order to inhabit his character, he locked himself up in a hotel room for weeks. He would do that. He liked to dive into his characters, but this time he really took it up a notch.

The hospital scene is interesting because when he was a kid, his sister Kate liked to dress him up as a nurse. He was really funny like that. He also was in the movie. This is a make-up test which was done eight months before. Before the end of the shooting he wrote ‘bye bye’ on the back of the page. It was hard to see this.